2 Engineering
2.5 Mains chokes
DB1 variable frequency drive
11/20 MN040031EN
Eaton.com
41
2.5 Mains chokes
Mains chokes reduce the total harmonic distribution (THD) and mains feed-
back. The apparent current on the mains side is then reduced by around
30 %.
Towards the variable frequency drive, the mains chokes dampen the interfe-
rence from the supply network. This increases the electric strength of the
variable frequency drive and lengthens the lifespan (diodes of the mains
power rectifier, internal DC link capacitors).
T
￫
It is not necessary to use mains chokes in order to run the DA1
variable frequency drive.
However, we recommend using a mains choke if the electrical
supply system’s quality is not known:
•
Large voltage peaks (e.g., when switching large loads
directly)
•
Correction systems (without series inductors)
•
Power supplied via conductor bar or slip ring systems
(e.g., overhead cranes)
While planning the project, consider that a mains choke is only
assigned to a single variable frequency drive for decoupling.
When using an adapting transformer (assigned to a single variable
frequency drive), a mains choke is not necessary.
Mains chokes are designed based on the mains-side input current
(I
LN
) of the variable frequency drive.
￫
When the variable frequency drive is operating at its rated cur-
rent limit, the mains choke at a u
K
value of about 4 % causes the
maximum possible output voltage U
2
of the variable frequency
drive to be reduced to about 96 % of the mains voltage U
LN
.
￫
For the rated mains chokes for DB1 variable frequency drives,
please refer to